The eight limbs of Yoga
Patanjali calls his advice 'ashtanga yoga', or the eight limbs of yoga. These are steps towards the goal, not sequential but fully interrelated, each reinforcing the other. Patanjali has significantly described them as limbs because, in any body, the limbs that constitute it grow in an organic, proportionate and concurrent manner till full development is reached.
The disciplines are yama (moral commandments), niyama (observances of conduct), asana (posture), pranayama (breathing exercises), pratyahara (withdrawal of the senses), dharana (concentration), dhyana (meditation) and samadhi (the settled mind or total -absorption).
YAMA - The five commandments
The yamas are five universal laws.
Ahimsa or non-violence extends way beyond its usual physical connotation. True non-violence, which is really freedom from fear and anger, is an inner state of quietitude, producing pure, unprejudiced action.
Satya is truth in thought, word and deed.
Asteya means `not stealing' which, in a wider sense, is not claiming anything that does not belong to us. To put it differently, we, as fully evolved spiritual selves, should not hanker after mundane objects.
Brahmacharya is again misunderstood as just physical celibacy. It is much more than that: it is the transcendence of all desires, thus leading to an enormous store of energy that has not been dissipated.
Aparigraha is living in a state of non-attachment, without coveting anything. As Shankaracharya points out, it is a difficult achievement: "The body has become old, the sight feeble, the bones weak, the flesh weak, the spirit dull, but man still does not give up desires."
NIYAMA - The right conduct
The niyamas are rules for living, also five in number.
Saucha is cleanliness or purity: both physical, to maintain the body and mind at their optimum best, and spiritual, to achieve a simple and unsullied awareness.
Santosa is contentment. The content man knows what he wants and how to achieve it and, therefore, is undisturbed by internal and external factors.
Tapas means blaze or fire. It is the burning commitment or desire to reach the pristine state. It is often described as the purification of desires by self-discipline and austerity.
Swadhyaya is the study of oneself, not in any narrow narcissistic manner, but as being conducive to reaching one's inner spiritual being.
Ishwarapranidhana is total, unconditional devotion and surrender to a higher infinite power. Sri Aurobindo says: "The manifestation of the higher forces takes place only if there is total humility and surrender."